Solid state electrolyte can be divided into organic, inorganic, organic-inorganic composite electrolytes. However, the conductivity of organic polymer solid state electrolyte (for example, PEO, PAN) is low (<10−5 S/cm). Although the inorganic solid state electrolyte (for example, LLZO, LLTO, LAGP) has high conductivity (about 10−3 S/cm), the interface resistance between the inorganic solid state electrolyte and the electrode is high. In addition, the traditional inorganic ceramic electrolyte is very brittle and has poor film-forming ability and poor mechanical properties and cannot be continuously processed. Although organic-inorganic composite electrolyte can decreases the interface resistance, the conductivity is decreased due to the addition of the organic polymer.
Therefore, a quasi-solid state electrolyte (QSSE) is derived as a fourth type of solid state electrolyte. That is, in addition to the organic-inorganic composite electrolyte, a small amount of liquid electrolyte (<5 wt %) is added to increase ionic conductivity.
However, the presence of liquid electrolytes may cause problems such as liquid leakage, flammable, poor cycle life, gassing, not resistant to high temperature. Also, the problem of high interface resistance of solid state electrolytes still exists. Therefore, a novel electrolyte is currently needed to solve the above shortcomings.